Out-of-bounds read vulnerability in GT21 model of GOT2000 series (GT2107-WTBD V01.39.000 and earlier, GT2107-WTSD V01.39.000 and earlier, GT2104-RTBD V01.39.000 and earlier, GT2104-PMBD V01.39.000 and earlier, and GT2103-PMBD V01.39.000 and earlier), GS21 model of GOT series (GS2110-WTBD V01.39.000 and earlier, GS2107-WTBD V01.39.000 and earlier, GS2110-WTBD-N V01.39.000 and earlier, and GS2107-WTBD-N V01.39.000 and earlier), and Tension Controller LE7-40GU-L series (LE7-40GU-L Screen package data for CC-Link IEF Basic V1.00, LE7-40GU-L Screen package data for MODBUS/TCP V1.00, and LE7-40GU-L Screen package data for SLMP V1.00) allows a remote attacker to cause a denial-of-service (DoS) condition by sending a specially crafted packet. As a result, deterioration of communication performance or a denial-of-service (DoS) condition of the TCP communication functions of the products may occur.